Chain hoist governor



Sept. 3, 1963 R; H. GREEGOR CHAIN HoIsT GOVERNOR rFiled Feb; 12, 1959 for shorter doors.

United States Patent O 3,102,580 CHAIN HIST GOVERNGR Ralph H. Greegor, Columbus, Ohio, assigner to The Kinnear Manufacturing Company, Columbus, Gino, a corporation of Ohio Filed Feb. 12, 1959, Ser. No. 792,739 3 Claims. (Cl. 16th- 133) This invention relates to rolling doors or curtains, and is particularly concerned with an arrangement for controlling :the speed of descent of such doors.

Many rolling doors and curtainsare manually operated and since the door or curtain represents considerable weight, it is at least partially oounterbalanced, usually by springs. In the event of failure of any of the springs, the curtain `or `door then has a tendency to come down more rapidly than is desired which might damage the door and could even cause personnel injury.

With the foregoing in mind, a principal object of the present invention is the provision of a simple control arrangement for a rolling door or curtain which tends to retard downward movement of the door and thus tends to prevent the door from descending too rapidly.

Another object of this invention is the provision of a sort of governor control to limit the downward speed of movement of a rolling door so that this speed cannot become excessive even if the counterbalancing means becomes partially inoperative.

The counterbalancing means employed with doors of this nature are ordinarily coiled springs, and since such springs have a substantially constant modulus, the torque of lthe springs will vary directly with the number of turns of the drum. The out of balance condition of the curtain, however, does not vary in this manner because the uncoiled portion of the curtain is hanging vertically downwardly in the door opening. Thus, a condition of unbalance is established when the curtain moves downwardly which increases as the curtain approaches a level i or height at a short distance above the bottom of the j opening. This unbalanced condition is more pronounced as the height of the door increases because the length of curtain hanging in the door opening will be greater than Accordingly, and particularly for high doors, it may be desirable to regulate the speed with which the door or curtain descends.

Thus, another object of this invention is the provision of an arrangement for oifsetting the unbalanced condition created as a rolling door moves down thereby to control the downw-ard speed Kof the door but which arrangement does not interfere wtih the normal operation of the door.

A. still further object of this invention is the provision of a 'relatively inexpensive, simple arrangement that can readily be incorporated in a rolling door operating mechanis-n1 to control the speed of movement thereof but without interfering with the normal operation of the door.

A still further object of this invention is the provision of a speed controlling arrangement for a rolling door which can be incorporated either in new manufacture or in presently existing equipment.

These and other objects and advantages will become more apparent upon reference to the accompanying drawings in which:

FiGURE 1 is an end view looking `at the drive mechanism for a typical rolling door showing a control device according to this invention,

FIGURE 2 is a view looking at the drive end of the rolling door mechanism from inside the wall on which it is mounted,

FIGURE 3 is a vertical sectional View indicated by line 3-3 on FIGURE 1 showing the mounting of a portion of the control mechanism,

3,l02,580 Patented Sept. 3, 1963 ICC FIGURE 4 is a perspective View showing a cam -lever forming 'a part of the control mechanism,

FIGURE 5 is a view showing a modied construction, and

FIGURE 6 is a fragmentary view showing the manner in which an adjustment could be incorporated in the control device. v v

Referring to the drawings more in detail, `a rolling door or curtain structure with which the control arrangement of the present invention is adapted for use comprises, generally, a drum 10 on which the liexible Idoor or curtain is mounted so that by rotating the drum the door can either be raised or lowered. The drum is supported betweenend members 14 that are attached to wall 16 in which is located the opening to be closed by the door.

A hood 18 is provided that encloses the drum lil and which extends from one end frame to the other.

Within drum v10, `according to known practices, there are counterbalance springs l2 which bias drum 10 in a direction so as to counterbalance the weight of the door or curtain.

For rotating the drum there is provided a hand chain Ztl running over a sprocket 22 fwhich is tixed to the same lshaft as a pinion 24 which meshes with a gear 26. Gear 26 is iiXed to the same shaft as a smaller gear 28 which meshes with a larger gear 31 attached to drum 10. It will be evident that movement of the chain Ztl will cause rotation of the drum and will thus cause the door either to raise or lower.

According to the present invention there is provided means vfor preventing the drum from rotating at excessive speed should some of the counterbalance springs slip or break or otherwise tail. This control mechanism takes the form of a cam lever 30 pivoted on a pin 32 extending outwardly horizontally lfrom a bracket plate 34 that is attached to the `adjacent one of the end members 14. Cam lever 30 has an upstanding cam portion 36 thereon disposed in the path of the teeth 3S of sprocket 22. The uppermost position of lever 30 is determined by a stop member 40 toward which the lever is biased by a compression spring 42.

The detailed `construction of the support of the cam lever is illustrated in FIGURE 3 where it will be seen that pin 32 is welded in a collar 44 which, in turn, is welded to the bracket plate 34. A washer 46 and a cotter pin 48 hold the cam lever 30 on the pin so that it is freely swingable thereon.

In operation, the sprocket 22 is turned clockwise, as it is viewed in FIGURE l, to rotate the drum 10 .in a direction to raise the door, and is rotated counterclockwise to turn drum 10 in a direction to lower the door. The cam portion 36, it will be observed, is so formed that when sprocket 22 is turning clockwise to raise the door the cam portion presents an incline of relatively small degree so that the sprocket can be rotated relatively easily. The cam lever is thus substantially ineffective while the door is being raised. When the sprocket is rotated counterclockwise, however, the cam portion 36 presents a relatively steep incline, and this inhibits rotation of sprocket 22.

The balance of the `door against the counterbalance springs, however, is such that the door has a natural tendency to move `downwardly Ibut when the sprocket is being manually operated to lower the door, the resistance offered by cam portion 36 of the cam lever does not prevent the door from being readily lowered.

However, should some of the counterbalance springs fail, in which case the door would be strongly biased in the downward direction by its own weight, the steep incline on the one side of the cam portion will prevent the sprocket from rotating at more than a safe speed. Thus, the door, even upon the failure of some of the counterbalance springs, can be safely operated until such time as the springs can be replaced.

The arrangement of FIGURES 1 through 4 shows a cast cam lever but the lever can also be fabricated by welding, as indicated in FIGURE 5, wherein the cam lever 50 consists of a piece of tubing 52 to which is welded a bar 54 and to the top of which is Welded a short member 56 bent to the desired configuration 'to present about the proper angles on the opposite sides. As an example of angles that might be employed, the steep side of the cam portion might be at an angle of 45 from the llever, and the other side might be at an angle of These angles are exemplary and do not represent limiting Values.

The effectiveness Iof the cam lever in either of the modications illustrated may be varied somewhat by providing an yadjustable stop screw 37, as illustrated in FIG- URE 6, which threads through the end of the lever opposite its pivotal support so as to abut stop 4t). Adjustment of stop screw 37 will determine the overlap of the cam portion of the lever with the sprocket teeth, thus determining the amount of resistance offered by the rotation of the sprocket and, therefore, of the drum and door.

It will be understood that this invention is susceptible to modification in `order to adapt it to different usages and conditions and, accordingly, it is desi-red to comprehend such modications within this invention as may fall within the scope of the appended claims.

I uclaim:

1. The combination, with a rolling door having a drum Iand 'door connected with the drum to be rolled up thereon, the `said drum being provided with counterbalancing means, a manually operated sprocket, reduction gearing connecting the sprocket with the drum so that rotation of the sprocket in one direction will turn the drum to raise the `door While lrotation of the sprocket in the other direction will turn the drurn to lower the door, of a support plate adjacent the sprocket, land cam means on the plate resiliently urged toward the sprocket so as to engage the teeth of the sprocket, said cam being operable to resist rotation of the sprocket at least in said other direction thereby to tend to limit the speed of descent of the door upon partial failure of the said counterbalance means, said cam means having inclined faces that are engaged by the teeth of the sprocket with the incline on the side of the cam means engaged by the sprocket teeth when the sprocket is turning in its said other direction `being at substantially a steeper angle than the incline on the lother side, said support plate being detachably mounted on the ldoor structure.

2. `In a brake device for a rolling door having a drum and a door connected with the drum to be rolled up thereon, the said drum being provided with counterbalancing means, a sprocket, a chain engaging one side of the sprocket for manual actuation thereof, reduction gearing connecting the sprocket with the drum so that rotation of the sprocket in one direction will turn the drum to raise the door while rotation of the sprocket in the other direction will turn the drum to lower the door, a support plate adapted for mounting adjacent the sprocket, a lever pivotally supported on the plate adjacent the other side tof the sprocket, a spring urging the lever toward the sprocket, and a cam on Ithe lever positioned to be engaged by the teeth of the sprocket as the sprocket rotates, the incline of the cam on the side engaged by the teeth when the sprocket is turning in 'the said other direction being substantially steeper than the other side of the cam whereby resistance to rotation of the sprocket in said other direction is greater rthan when it is turning in the said one direction, there being means on the plate forming an adjustable stop for adjusting the innermost position of the lever as it is urged toward the sprocket thereby to Vary the amount of overlap of the cam and the sprocket teeth thus to adjust the resisting action of the cam on the sprocket.

3. In a rolling door having a drum, a rollable door connected to said drum to be rolled thereupon, counterbalancing means for said drum, a sprocket geared with said drum, an operating chain engaging one side of said sprocket for lowering and lifting said door in rotating said drum, a stationarily mounted support plate, a lever pivotally supported on said plate adjacent the other side of' said sprocket, an asymmetrically shaped cam on said lever to be engaged by the teeth of said sprocket upon rotation thereof, and a spring urging said lever toward said sprocket and cooperating with said cam for providing resistance against rotation of said sprocket, the magnitude of this resistance being considerably larger yfor a rotation lowering said door, than for a rotation lifting said door.

References Cited in the le of this patent UNITED STATES PATENTS 643,286 Feiker Feb. 13, 1900 1,268,914 Barry et al June 11, 1918 

1. THE COMBINATION, WITH A ROLLING DOOR HAVING A DRUM AND DOOR CONNECTED WITH THE DRUM TO BE ROLLED UP THEREON, THE SAID DRUM BEING PROVIDED WITH COUNTERBALANCING MEANS, A MANUALLY OPERATED SPROCKET, REDUCTION GEARING CONNECTING THE SPROCKET WITH THE DRUM SO THAT ROTATION OF THE SPROCKET IN ONE DIRECTION WILL TURN THE DRUM TO RAISE THE DOOR WHILE ROTATION OF THE SPROCKET IN THE OTHER DIRECTION WILL TURN THE DRUM TO LOWER THE DOOR; OF A SUPPORT PLATE ADJACENT THE SPROCKET, AND CAM MEANS ON THE PLATE RESILIENTLY URGED TOWARD THE SPROCKET SO AS TO ENGAGE THE TEETH OF THE SPROCKET, SAID CAM BEING OPERABLE TO RESIST ROTATION OF THE SPROCKET AT LEAST IN SAID OTHER DIRECTION THEREBY TO TEND TO LIMIT THE SPEED OF DESCENT OF THE DOOR UPON PARTIAL FAILURE OF THE SAID COUNTERBALANCE MEANS, SAID CAM MEANS HAVING INCLINED FACES THAT ARE ENGAGED BY THE TEETH OF THE SPROCKET WITH THE INCLINE ON THE SIDE OF THE CAM MEANS ENGAGED BY THE SPROCKET TEETH WHEN THE SPROCKET IS TURNING IN ITS SAID OTHER DIRECTION BEING AT SUBSTANTIALLY A STEEPER ANGLE THAN THE INCLINE ON THE OTHER SIDE, SAID SUPPORT PLATE BEING DETACHABLY MOUNTED ON THE DOOR STRUCTURE. 